1. Field of the Invention
The present invention relates to an optical fiber used as an optical transmission line in a Wavelength Division Multiplexing (WDM) transmission system.
2. Related Background Arts
A WDM transmission system can transmit a large volume of information at high bit rates using light signals each having a different wavelength. Restraining nonlinear optical phenomena and widening a light signal range are important problems in the WDM transmission system.
The optical fiber disclosed in the Japanese patent application laid open 11-281840 has a dispersion null point at the nominal wavelength value of xcex0=1400 nm with an OH absorption peak, and the values of chromatic dispersion of this fiber are of negative sign in the 1310 nm window and of positive sign in the 1550 nm window. In both windows this optical fiber provides for values of dispersion sufficiently high to maintain optical non-linear effects, for example four-wave mixing generation, within tolerable limits for WDM operation, and can widen a light signal range as well. This optical fiber is hereinafter called xe2x80x9cthe 1380 nm zero-dispersion fiberxe2x80x9d.
Chromatic dispersions of the 1380 nm zero-dispersion fiber are positive in a wide wavelength range (1450-1620 nm) that includes S-band (1450-1530 nm), C-band (1530-1560 nm) and L-band (1560-1620 nm). In the past there was no dispersion compensating optical fiber which compensated the chromatic dispersions of the 1380 nm zero-dispersion fiber at all of the wavelengths in the range of 1450 nm to 1620 nm.
It is an object of the present invention to provide an optical fiber whose chromatic dispersions have an opposite sign relative to those of the 1380 nm zero-dispersion fiber at all of the wavelengths in the range of 1450 nm to 1620 nm, and can compensate the dispersions of 1380 nm zero-dispersion fiber.
In order to achieve this and other objects, an optical fiber is provided whose chromatic dispersions are negative at all of the wavelengths in the range of 1450 nm to 1620 nm, having chromatic dispersions of xe2x88x927 psxc2x7nmxe2x88x921xc2x7km1xe2x88x92or more but xe2x88x921 psxc2x7nmxe2x88x921xc2x7km1xe2x88x92or less at a wavelength of 1450 nm, xe2x88x9212 psxc2x7nmxe2x88x921xc2x7km1xe2x88x92or more but xe2x88x925 psxc2x7nmxe2x88x921xc2x7km1xe2x88x92or less at a wavelength of 1550 nm and xe2x88x9217 psxc2x7nmxe2x88x921xc2x7km1xe2x88x92or more but xe2x88x926 psxc2x7nmxe2x88x921xc2x7km1xe2x88x92or less at a wavelength of 1620 nm.
The above and further objects and novel features of the invention will be more fully clarified from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention.